The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 85 inches, and a standard deviation of 14 inches. What is the probability that the mean annual precipitation during 49 randomly picked years will be less than 87.8 inches?
A) 0.4192
B) 0.0808
C) 0.5808
D) 0.9192

Question

Quizplus · Accepted Answer

The standard error of the mean is 14/sqrt(49) = 2. The z-score for 87.8 is (87.8-85)/2 = 1.4. The probability of a z-score less than 1.4 is approximately 0.9192.

The Annual Precipitation Amounts in a Certain Mountain Range Are